AP Unit 3- Cells and Membranes

Cytoplasm

Jelly-like fluid inside the cell that holds organelles and supports reactions.

Prokaryotic cell

Simple cell without a nucleus; DNA is free in the cytoplasm.

Nucleoid region

Area in a prokaryotic cell where the DNA is located.

Eukaryotic cell

Complex cell with a nucleus and membrane-bound organelles.

Cytosol

The liquid part of the cytoplasm where reactions occur.

Plasma membrane

Thin barrier that controls what enters and leaves the cell.

Nucleus

Organelle that stores DNA and controls cell activities.

Nucleolus

Small region inside the nucleus where ribosomes are made.

Ribosome

Site of protein synthesis; can be free or attached to ER.

Endomembrane system

Group of organelles (ER

Smooth endoplasmic reticulum (ER)

Makes lipids and detoxifies harmful substances.

Rough endoplasmic reticulum (ER)

Has ribosomes; makes and folds proteins.

Glycoprotein

Protein with sugar attached; used in cell recognition and signaling.

Golgi apparatus

Modifies

Central vacuole

Large storage sac in plant cells for water and nutrients.

Peroxisome

Breaks down fatty acids and detoxifies harmful substances.

Mitochondrion

Produces energy (ATP) from glucose during cellular respiration.

Chloroplast

Found in plants; converts sunlight into chemical energy (photosynthesis).

Cytoskeleton

Network of protein fibers that gives the cell shape and helps movement.

Microtubules

Thick hollow tubes that maintain cell shape and help move organelles.

Microfilaments

Thin protein threads that support cell shape and movement.

Centriole

Helps organize microtubules during cell division in animal cells.

Flagella

Long whip-like structures that move the cell.

Cilia

Short hair-like structures that move substances or the cell itself.

Cell wall

Rigid outer layer that supports and protects plant

Extracellular matrix

Network outside animal cells for support

Plasmodesmata

Channels between plant cells for communication and transport.

Tight junctions

Seal cells together to prevent leakage between them.

Desmosomes

Anchor cells together like rivets

Gap junctions

Channels between animal cells for communication and exchange.

Selective permeability

Property of membranes to allow some substances to pass but not others.

Fluid mosaic model

Describes the flexible structure of the cell membrane with moving proteins and lipids.

Integral proteins

Proteins embedded in the membrane that transport molecules.

Peripheral proteins

Proteins on the membrane surface for signaling or support.

Diffusion

Movement of molecules from high to low concentration.

Concentration gradient

Difference in concentration of a substance across a space.

Passive transport

Movement of substances across the membrane without energy.

Hypertonic

Solution with higher solute concentration; water moves out of the cell.

Hypotonic

Solution with lower solute concentration; water moves into the cell.

Isotonic

Solution with equal solute concentration; no net water movement.

Osmosis

Diffusion of water through a selectively permeable membrane.

Turgid

Firm cell due to water entering (in plant cells).

Flaccid

Limp cell due to water loss (in plant cells).

Facilitated diffusion

Passive transport using transport proteins.

Active transport

Movement of molecules using energy (ATP) against the gradient.

Membrane potential

Voltage difference across a cell membrane due to ion movement.

Cotransport

Coupled transport where one substance’s movement drives another’s.

Exocytosis

Process of releasing materials from a cell via vesicles.

Phagocytosis

“Cell eating” — cell engulfs large particles or other cells.

Pinocytosis

“Cell drinking” — cell takes in fluid and small molecules.

Endocytosis

General process of taking materials into the cell by forming vesicles.